Scalping accidents with shielded PTO units: four case reports.

1. The type of guard on a hay baler, noted as the inverted U-shield, does not completely enclose the driveline. The underneath side is extremely hazardous, and entanglement is likely. 2. Wind speed and direction, height of the driveline, and workers' hair length may contribute to the risk for entanglement. 3. This type of driveline warrants retrofitting and recognition of the need to shut off the driveline before approaching it. 4. Operators should periodically examine machinery to determine whether unguarded areas on the machine pose a hazard, and contact an authorized equipment dealer to determine if any of their machinery requires a retrofit shield or other safety modification recommended by the manufacturer.